Transcription factor CrWRKY42 coregulates chlorophyll degradation and carotenoid biosynthesis in citrus.

Chlorophyll degradation and carotenoid biosynthesis, which occur almost simultaneously during fruit ripening, are essential for the coloration and nutritional value of fruits. However, the synergistic regulation of these 2 processes at the transcriptional level remains largely unknown. In this study, we identified a WRKY transcription factor, CrWRKY42, from the transcriptome data of the yellowish bud mutant "Jinlegan" ([Citrus unshiu × C. sinensis] × C. reticulata) tangor and its wild-type "Shiranui" tangor, which was involved in the transcriptional regulation of both chlorophyll degradation and carotenoid biosynthesis pathways. CrWRKY42 directly bound to the promoter of ß-carotene hydroxylase 1 (CrBCH1) and activated its expression. The overexpression and interference of CrWRKY42 in citrus calli demonstrated that CrWRKY42 promoted carotenoid accumulation by inducing the expression of multiple carotenoid biosynthetic genes. Further assays confirmed that CrWRKY42 also directly bound to and activated the promoters of the genes involved in carotenoid biosynthesis, including phytoene desaturase (CrPDS) and lycopene ß-cyclase 2 (CrLCYB2). In addition, CrWRKY42 could bind to the promoters of NONYELLOW COLORING (CrNYC) and STAY-GREEN (CrSGR) and activate their expression, thus promoting chlorophyll degradation. The overexpression and silencing of CrWRKY42 in citrus fruits indicated that CrWRKY42 positively regulated chlorophyll degradation and carotenoid biosynthesis by synergistically activating the expression of genes involved in both pathways. Our data revealed that CrWRKY42 acts as a positive regulator of chlorophyll degradation and carotenoid biosynthesis to alter the conversion of citrus fruit color. Our findings provide insight into the complex transcriptional regulation of chlorophyll and carotenoid metabolism during fruit ripening.

Multiomics-based dissection of citrus flavonoid metabolism using a Citrus reticulata × Poncirus trifoliata population.

Deciphering the genetic basis of plant secondary metabolism will provide useful insights for genetic improvement and enhance our fundamental understanding of plant biological processes. Although citrus plants are among the most important fruit crops worldwide, the genetic basis of secondary metabolism in these plants is largely unknown. Here, we use a high-density linkage map to dissect large-scale flavonoid metabolic traits measured in different tissues (young leaf, old leaf, mature pericarp, and mature pulp) of an F1 pseudo-testcross citrus population. We detected 80 flavonoids in this population and identified 138 quantitative trait loci (QTLs) for 57 flavonoids in these four tissues. Based on transcriptional profiling and functional annotation, twenty-one candidate genes were identified, and one gene encoding flavanone 3-hydroxylase (F3H) was functionally verified to result in naturally occurring variation in dihydrokaempferol content through genetic variations in its promoter and coding regions. The abundant data resources collected for diverse citrus germplasms here lay the foundation for complete characterization of the citrus flavonoid biosynthetic pathway and will thereby promote efficient utilization of metabolites in citrus quality improvement.

Selective oxidation of benzyl alcohols to benzoic acid catalyzed by eco-friendly cobalt thioporphyrazine catalyst supported on silica-coated magnetic nanospheres.

A novel magnetically recoverable thioporphyrazine catalyst (CoPz(S-Bu)8/SiO2@Fe3O4) was prepared by immobilization of the cobalt octkis(butylthio) porphyrazine complex (CoPz(S-Bu)8) on silica-coated magnetic nanospheres (SiO2@Fe3O4). The composite CoPz(S-Bu)8/SiO2@Fe3O4 appeared to be an active catalyst in the oxidation of benzyl alcohol in aqueous solution using hydrogen peroxide (H2O2) as oxidant under Xe-lamp irradiation, with 36.4% conversion of benzyl alcohol, about 99% selectivity for benzoic acid and turnover number (TON) of 61.7 at ambient temperature. The biomimetic catalyst CoPz(S-Bu)8 was supported on the magnetic carrier SiO2@Fe3O4 so as to suspend it in aqueous solution to react with substrates, utilizing its lipophilicity. Meanwhile the CoPz(S-Bu)8 can use its unique advantages to control the selectivity of photocatalytic oxidation without the substrate being subjected to deep oxidation. The influence of various reaction parameters on the conversion rate of benzyl alcohol and selectivity of benzoic acid was investigated in detail. Moreover, photocatalytic oxidation of substituted benzyl alcohols was obtained with high conversion and excellent selectivity, specifically conversion close to 70%, selectivity close to 100% and TON of 113.6 for para-position electron-donating groups. The selectivity and eco-friendliness of the biomimetic photocatalyst give it great potential for practical applications.

Targeting bladder tumor cells in voided urine of Chinese patients with FITC-CSNRDARRC peptide ligand.

OBJECTIVE: To study the practicality of the FITC-CSNRDARRC peptide ligand (containing the Cys-Ser-Asn-Arg-Asp-Ala-Arg-Arg-Cys nonapeptide) in diagnosing and monitoring bladder tumors. MATERIALS AND METHODS: Between March 2011 and September 2011, 80 consecutive patients with radiographic abnormalities, localizing hematuria, other symptoms, or signs were studied using the FITC-CSNRDARRC ligand, urinary cytology (UC), and fluorescence in situ hybridization (FISH). The sensitivity and specificity of these three technologies were determined and compared. Cystoscopy and tissue biopsy were taken as the "gold standards" for bladder tumor diagnosis in this study. RESULTS: Twenty-nine out of 80 patients were diagnosed with a bladder tumor via histopathological examination. The FITC-CSNRDARRC ligand was positive in 23 out of 29 bladder tumor patients and produced false negatives in six (20.69%) patients. The UC was positive in six out of 29 bladder tumor patients and produced false negatives in 23 (79.31%) patients. The FISH was positive in 21 out of 29 bladder tumor patients and produced false negatives in eight (27.59%) patients. The overall sensitivity as verified by the FITC-CSNRDARRC ligand was much higher than in UC (79.31% versus 20.69%, P < 0.001) and was slightly higher than in FISH (79.31% versus 72.41%, P = 0.625). The sensitivity of FISH was significantly higher than that of UC (72.41% versus 20.69%, P < 0.001). Sensitivities of the FITC-CSNRDARRC ligand and UC by grade were 58.33% versus 8.3% for low-grade (LG) tumors (P = 0.031) and 94.12% versus 29.41% for high-grade (HG) tumors (P = 0.003), respectively. The advantage was maintained in terms of the detection of invasive tumors between the FITC-CSNRDARRC ligand and UC (90.48% versus 23.81%, P = 0.001) as well as between FISH and UC (85.71% versus 23.81%, P = 0.003). The specificities for the FITC-CSNRDARRC ligand, UC, and FISH were 100%. CONCLUSION: Results show that the FITC-CSNRDARRC ligand is a promising noninvasive tool for diagnosis and surveillance in patients suspected of having a new bladder tumor.